JPH08192447A - Injection mechanism of injection molding machine - Google Patents

Abstract

PURPOSE: To accurately measure substantial resin reaction force by a load cell. CONSTITUTION: A ball screw 28 is attached to a pusher plate 14 in a freely rotatable and axially immovable manner and rotationally driven not only to axially change the screwing position of the ball screw 28 to the ball nut 31 fixed to a rear plate 3 through a load cell 33 but also to move the pusher plate 14 pressing an injection screw along a guide rod 4. Since the ball screw 28 is supported to the pusher plate 14 in a freely rotatable manner, the reaction force of the rotary friction between the ball screw 28 and the ball nut 31 is not transmitted to the pusher plate 14 and the non-uniform contact of the pusher plate with the guide rod 4 is prevented and the slide resistance between both of them always becomes constant. Since slide resistance becomes unchanged, substantial resin reaction force can be accurately measured by a load cell 33 detecting the resultant of slide resistance and substantial resin reaction force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of an injection mechanism of an injection molding machine.

[0002]

2. Description of the Related Art A pusher plate is slidably attached to a guide rod provided in parallel with an injection axis, and a rotational movement of a ball screw is converted into a linear movement by a combination of a ball screw and a ball nut to press the pusher plate. An injection mechanism of an injection molding machine in which the injection screw is moved by is already known.

FIG. 5 is a partial sectional side view schematically showing an injection mechanism of a conventional injection molding machine. Reference numeral 1 is an injection cylinder 2
Is a fixed front plate, reference numeral 3 is a rear plate, and the front plate 1 and the rear plate 3 are integrally fixed by a guide rod 4 which also serves as a tie rod,
A pusher plate 6 having an injection screw 5 rotatably and axially immovably attached to the guide rod 4 is slidably attached via a bush 7.

On the back surface of the pusher plate 6,
A ball nut 9 is fixed so as not to be rotatable and axially movable via a load cell 8 for detecting a resin reaction force. The ball nut 9 is attached to the rear plate 3 side so as to be rotatable and axially immovable. It is screwed with the ball screw 10. In addition, in FIG. 5, the bearing 11 which is superposed in two rows between the rear plate 3 and the ball screw 10 is an angular bearing having an outer ring for supporting a resin reaction force acting on the inner ring from the left side in the drawing. ,
The bearing 12 is an angular bearing having an outer ring for supporting a force acting on the inner ring from the right side in the drawing. The inner ring of each bearing 11, 12 is fixed to the outer periphery of the ball screw 10, and each bearing 11, 12
The outer ring 12 is fixed to the inner circumference of a through hole provided in the center of the rear plate 3, and these bearings 11, 1
The ball screw 10 is held rotatably with respect to the rear plate 3 and is immovable in the axial direction.

An injection driving pulley 13 is fixed to the end of the ball screw 10 protruding from the rear surface of the rear plate 3, and a rotation driving means such as a motor (not shown) fixed to one side of the rear plate 3 is fixed. By rotating the ball screw 10 through the power transmission means such as a timing belt or the pulley 13, the ball nut 9 is fed, the pusher plate 6 is pressed through the load cell 8 and the injection screw 5 is axially moved. It is designed to be moved.

The load cell 8 needs to accurately measure the resin reaction force acting on the tip of the injection screw 5 at the time of injection or measurement, but in the conventional configuration example shown in FIG. 5, this is accurately measured. Is difficult to do.

Some of the rotational force of the ball screw 10 is transmitted to the ball nut 9 by the frictional force between the ball screw 10 and the ball nut 9, and is injected into the pusher plate 6 via the ball nut 9 and the load cell 8. This is because the rotational moment about the axis acts and the bush 7 comes into partial contact with the guide rod 4 to change the sliding resistance between the pusher plate 6 and the guide rod 4.

Since the load cell 8 is arranged on the force transmission path between the rear plate 3 and the pusher plate 6, more strictly speaking, the load cell 8 substantially acts on the tip of the injection screw 5. Instead of detecting the resin reaction force itself, the resultant force of the substantial resin reaction force acting on the tip of the injection screw 5 and the sliding resistance is detected as an apparent resin reaction force. Therefore, some kind of correction action is required to obtain a substantial resin reaction force, but the magnitude of the sliding resistance is the magnitude of the resin reaction force, that is,
Since the force that causes the frictional resistance between the ball screw 10 and the ball nut 9 and the magnitude of the rotational force of the ball screw 10 vary variously and do not become a uniform value, the magnitude of this sliding resistance is changed. It is virtually impossible to calculate the actual magnitude of the resin reaction force by adding or subtracting it to the detected value, or to perform the zero point correction of the load cell 8 so as to match the magnitude of the sliding resistance. This is possible, and as a result, the substantial resin reaction force acting on the tip of the injection screw 5 cannot be accurately measured.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a structure in which a pusher plate of an injection screw is slidably supported by a guide rod, and the pusher plate is interposed between the pusher plate and the guide rod. It is an object of the present invention to provide an injection mechanism of an injection molding machine which can always keep the magnitude of the sliding resistance acting on a constant value and accurately measure the substantial resin reaction force acting on the injection screw with a load cell.

[0010]

According to the present invention, a pusher plate for pressing an injection screw is provided with a ball screw rotatably and immovably in the axial direction, and a rear plate integral with a guide rod is provided with a load cell. The above object is achieved by a constitution characterized in that a ball nut is fixedly mounted, the ball screw is screwed into the ball nut, and the ball screw is rotationally driven to move the injection screw.

Further, a screw sleeve having an injection screw fixed thereto is attached to the pusher plate so as to be rotatable and axially immovable, and is fitted into the screw sleeve so as to be rotatable and axially immovable with respect to the screw sleeve. And a configuration in which
A ball screw sleeve having a ball screw fixed thereto is rotatably and axially immovably attached to the pusher plate, and further fitted into the ball screw sleeve so as to be rotatable and axially immovable with respect to the ball screw sleeve. With the configuration of supporting the shaft, the injection mechanism can be shortened and downsized.

Further, means for pivotally supporting the injection screw rotatably and axially immovable on the pusher plate and means for pivotally supporting the ball screw rotatably and axially immovably on the pusher plate are injected. With the configuration in which the pusher plate is superposed on the pusher plate along the axial direction, the magnitude of the sliding resistance acting between the pusher plate and the guide rod can be always kept constant as in the above.

When the respective means are superposed on the pusher plate along the injection axis direction, a first pusher plate and a second pusher plate which are arranged at a predetermined interval from each other in the injection axis direction are provided. Are integrally fixed to form a pusher plate, and the first pusher plate is provided with means for rotatably and immovably axially supporting the injection screw, while the second pusher plate is provided with Means are provided for rotatably and axially immovably supporting the ball screw. Alternatively, the first pusher plate and the second pusher plate are integrally fixed to each other so as to sandwich the rear plate with a predetermined space therebetween in the injection axis direction, and the first pusher plate is provided with the injection plate. Means for rotatably supporting the screw so as not to be axially movable and means for supporting the ball screw so as to be rotatable but not axially movable are provided, and the end of the ball screw is rotated on the second pusher plate. Means for freely supporting the shaft and means for rotationally driving the ball screw are provided.

[0014]

The ball screw rotatably and immovably mounted on the pusher plate pressing the injection screw is rotationally driven, and the screwing position of the ball screw with respect to the ball nut fixed to the rear plate via the load cell is set as the shaft. Change in direction. Since the ball screw is attached to the pusher plate so that it cannot move axially,
Due to the change in the screwing position, the pusher plate moves axially integrally with the ball screw with respect to the rear plate, and the injection screw attached to the pusher plate moves.

Since the ball screw is rotatably attached to the pusher plate, even if rotational friction is generated between the ball screw and the ball nut by rotationally driving the ball screw, the reaction force of the ball screw causes the pusher to move through the ball screw. It is not transmitted to the plate. Therefore, since no rotation moment about the injection axis is generated in the pusher plate and the pusher plate does not hit the guide rod evenly, the sliding resistance between the pusher plate and the guide rod is kept constant.

As a result of the constant sliding resistance, the detection accuracy of the substantial resin reaction force by the load cell is improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional side view schematically showing an injection mechanism of an embodiment to which the present invention is applied. Reference numeral 1 is a front plate on which the injection cylinder 2 is fixed, reference numeral 3 is a rear plate, and the front plate 1 and the rear plate 3 are integrally fixed by a guide rod 4 which also serves as a tie rod. A pusher plate 14 having an injection screw 5 rotatably and axially immovably attached to the center thereof is slidably attached via a bush 7.

In this embodiment, the outer races of the bearings 15 and 16 are fixed to the inner circumference of the through hole provided in the central portion of the pusher plate 14, and the inner races of the bearings 15 and 16 are further provided with an injection screw. The outer periphery of the screw sleeve 17 in which 5 is fixed is fixed. The bearing 15 is an angular bearing having an outer ring for supporting the force acting on the inner ring from the left side in the figure, and the bearing 16 is for supporting the force acting on the inner ring from the right side in the figure. It is an angular bearing with an outer ring. The outer rings of the bearings 15 and 16 are an annular mounting flange 22 for axially co-fastening these outer rings, and the mounting flange 2
2 for fixing 2 to the pusher plate 14
3 is integrally fixed to the inner circumference of the through hole provided in the central portion of the pusher plate 14, and the inner rings of the bearings 15 and 16 are externally threaded at the outer peripheral rear end of the screw sleeve 17. Ring-shaped fixing member 2 screwed onto
The screw sleeve 1 is fastened together by 4 in the axial direction.
It is integrally fixed to the outer circumference of 7.

As shown in FIG. 1, the injection screw 5 is integrally fixed to the front end surface of the screw sleeve 17 via a screw mounting plate 18 and a bolt 19, and the front end surface of the screw sleeve 17 has an annular shape. The screw rotating pulley 20 is integrally fixed via a bolt 21.

The bearing 2 is provided on the inner circumference of the screw sleeve 17 by an annular fixing member 25 which is screwed into a female screw threaded on the rear end of the inner circumference of the screw sleeve 17.
The outer races 6, 27 are fixed, and the outer circumferences of the tips of the ball screws 28 are fixed to the inner races of the bearings 26 and 27. The bearing 26 has an angular bearing having an outer ring for supporting a force acting on the inner ring from the left side in the figure, and the bearing 16 has an outer ring for supporting a force acting on the inner ring from the right side in the figure. It is an angular bearing. The inner rings of the bearings 26 and 27 are axially fastened together with the injection driving pulley 30 by an annular fixing member 29 that is screwed into a male screw threaded on the outer periphery of the tip of a ball screw 28 having a reduced diameter. It is fixed to the tip of the ball screw 28. The injection driving pulley 30 is attached to the reduced diameter portion of the tip of the ball screw 28 via spline fitting, and cannot rotate with respect to the ball screw 28.

That is, in the injection mechanism of this embodiment, the screw sleeve 17 having the injection screw 5 fixed thereto is attached to the pusher plate 14 so as to be rotatable and axially immovable, and is further fitted inside the screw sleeve 17. Thus, the ball screw 28 is supported so as to be rotatable and immovable in the axial direction.

On the other hand, a through hole for loosely fitting a ball nut 31 screwed with a ball screw 28 is provided in the central portion of the rear plate 3 which is integral with the guide rod 4, and a bolt 32 is provided on the rear surface of the rear plate 3 by a bolt 32. The ball nut 31 is fixed to the fixed annular load cell 33 via a bolt 34. Load cell 33 fixed to the rear plate 3
Receives a force acting in the axial direction of the ball nut 31 to cause bending, and converts the amount of bending into a voltage or the like, which is substantially equal to the sliding resistance acting between the guide rod 4 and the pusher plate 14. It is output to the control device of the injection molding machine as the resultant force with the resin reaction force.

Further, the screw rotation motor 35 and the injection drive motor (servo motor) 36 are symmetrical with respect to the attachment point of the injection screw 5 (the point where the central axis of the injection screw 5 and the pusher plate 14 intersect). Each pusher plate 14 is fixedly attached to both ends of the pusher plate 14 to balance the pusher plate 14.
Each motor 35, 36 has a respective drive pulley 37, 38
The pulleys 20 and 30 are rotationally driven by the timing belts 39 and 40 wound around.

Therefore, when measuring and kneading, the motor 3
When the motor 35 is driven to rotate while holding 6 at a predetermined rotation position, only the injection screw 5 rotates independently of the ball screw 28 to perform the kneading and kneading work, and the molten resin is attached to the tip of the injection cylinder 2. Is sent. Accordingly, the injection screw 5, pusher plate 14 and ball screw 28 are pressed in the backward direction. This pressing force is detected by the load cell 33 via the ball nut 31.
When the detected pressing force becomes equal to or higher than the set back pressure, the motor 36 is rotated by a set predetermined amount in the direction in which the injection screw 5 is retracted, and the rotation position is held. When the motor 36 rotates, the ball screw 28 rotates via the pulley 38, the timing belt 40, and the pulley 30.
8, the pusher plate 14 and the injection screw 5 are retracted by a predetermined amount. As a result, the volume of the molten resin accumulated at the tip of the injection cylinder 2 increases and the pressure of the molten resin decreases, so that the force for retracting the injection screw 5 and the like decreases. Further, if the rotation of the injection screw 5 by the motor 35 is continued, the force for retracting the injection screw 5 and the like increases as described above, and the above-described operation is performed. By repeating this operation, metering and kneading is performed.

On the other hand, at the time of injection, if only the motor 36 is rotationally driven while the motor 35 is stopped, only the ball screw 28 rotates independently of the injection screw 5, and the balls fixed on the rear plate 3 are rotated. The axial screwing position of the ball screw 28 with respect to the nut 31 changes. As a result, the pusher plate 14 to which the ball screw 28 is attached so as to be immovable in the axial direction advances, and the injection screw 5 advances in the injection cylinder 2 for injection. At this time, the reaction force (injection pressure) received by the injection screw 5 from the resin is detected by the load cell 33 via the pusher plate 14, the ball screw 28, and the ball nut 31.

At this time, a certain amount of frictional resistance acts on the screwing surface of the ball screw 28 and the ball nut 31 in the circumferential direction (rotational direction), so that the reaction force corresponding to this frictional resistance causes a rotational moment about the axis. Acts as an external force on the ball screw 28 itself. However, since the tip of the ball screw 28 is rotatably attached to the pusher plate 14 via the bearings 26, 27, etc.,
This rotational moment is not transmitted to the pusher plate 14 itself. Therefore, the bush 7 provided on the pusher plate 14 is not pressed against the guide rod 4 by the rotation moment around the injection axis and does not hit the guide rod 4 one-sided.
The sliding resistance between No. 4 and 4 is always maintained at a constant value regardless of the magnitude of the frictional resistance in the circumferential direction that acts on the screwing surface between the ball screw 28 and the ball nut 31.

The load cell 33 detects the resultant force of the sliding resistance acting between the guide rod 4 and the pusher plate 14 and the substantial resin reaction force. Since the sliding resistance acting between the pusher plate 14 and the pusher plate 14 is always a constant value (known value), it is easy to measure a substantial resin reaction force. For example, when only the injection pressure is measured, the force corresponding to the sliding resistance is subtracted to mechanically load the load cell 33.
It suffices to perform the zero point correction of the above, and when measuring the injection pressure and the back pressure, subtract the sliding resistance force from the detected value at the time of injection to obtain the actual injection pressure. At the time of measurement (when the screw is retracted), a force corresponding to the sliding resistance may be added to the detected value to obtain a substantial back pressure.

In this embodiment, the screw sleeve 17
Since the ball screw 28 is axially supported by being internally fitted to the bearings 15 and 16 that rotatably hold the screw sleeve 17 and the bearings 26 and 27 that rotatably hold the ball screw 28, they are concentrically arranged. Therefore, there is an effect that the total length of the entire injection mechanism can be shortened as compared with those of FIGS. 3 and 4 described later.

FIG. 2 is a partial sectional side view showing another embodiment of the injection mechanism to which the present invention is applied. A ball screw sleeve 41 having a ball screw 28 fixed thereto is rotatable with respect to the pusher plate 14 and axially. The embodiment is different from the embodiment shown in FIG. 1 in that the injection screw 5 is mounted so as to be immovable, and is fitted in the ball screw sleeve 41 so as to be rotatable and axially immovable so as not to move (FIG. 1). In the configuration example of No. 1, the ball screw 28 is provided by being fitted into the screw sleeve 17).

Front plate 1, injection cylinder 2, rear plate 3, guide rod 4, pusher plate 1
4, the structure of the ball nut 31, the load cell 33, etc. is the same as that of the embodiment shown in FIG.

In this embodiment, the outer rings of the bearings 42 and 43 are fixed to the inner circumference of the through hole provided in the central portion of the pusher plate 14, and the ball screws 28 are attached to the inner rings of the bearings 42 and 43. The bolt 44
The outer periphery of the ball screw sleeve 41 fixed in (4) is fixed. The bearing 42 is an angular bearing having an outer ring for supporting a force acting on the inner ring from the left side in the figure, and the bearing 43 is an angular bearing for supporting an inner ring on the right side in the figure. It is equipped with an angular bearing. Bearings 42 and 43
Of the outer ring of the pusher plate 14 is provided in the central portion of the pusher plate 14 by an annular mounting flange 47 for fastening the outer rings together in the axial direction and a bolt 48 for fixing the mounting flange 47 to the pusher plate 14. Is integrally fixed to the inner circumference of the through hole, and the inner rings of the bearings 42 and 43 are formed by the ball screw sleeve 4
An axial fixing member 49 screwed into a male screw threaded on the central outer peripheral portion of the No. 1 is axially fastened together and integrally fixed to the outer periphery of the ball screw sleeve 41. Further, an injection driving pulley 45 formed in an annular shape is integrally fixed to the front end surface of the ball screw sleeve 41 via a bolt 46.

The outer rings of the bearings 51 and 52 are fixed to the inner circumference of the ball screw sleeve 41 by an annular fixing member 50 that is screwed into a female screw threaded on the rear end of the inner circumference of the ball screw sleeve 41. , Bearing 51
The small diameter portion of the screw sleeve 53 is fixed to the inner races of 52 and 52. The bearing 51 has an angular bearing having an outer ring for supporting a force acting on the inner ring from the left side in the figure, and the bearing 52 has an outer ring for supporting a force acting on the inner ring from the right side in the figure. It is an angular bearing. Bearing 51
The inner rings of 52 and 52 are integrally fixed to the screw sleeve 53 by an annular fixing member 54 that is screwed into a male screw threaded on the outer periphery of the tip of the small diameter portion of the screw sleeve 53. A screw rotation pulley 56 is integrally attached to the front end surface of the screw sleeve 53 by a bolt 55, and the injection screw 5 is integrally attached via a bolt 57 and a screw attachment plate 58. .

A screw rotating motor 35 and an injection driving motor (servo motor) 36 are fixed to both ends of the pusher plate 14 with the central point of the pusher plate as a symmetry point, as in the embodiment shown in FIG. Mounted and balancing pusher plate 14. Each of the motors 35 and 36 rotationally drives the pulley 56 and the pulley 45 by the timing belts 39 and 40 wound around the drive pulleys 37 and 38, respectively.

Ball screw 28 as in the previous embodiment
Is rotatably attached to the pusher plate 14, so that when the ball screw 28 is rotationally driven, the frictional resistance in the circumferential direction that acts on the screwing surface between the ball screw 28 and the ball nut 31 is the rotational moment about the injection axis. Does not act on the pusher plate 14, and the sliding resistance between the guide rod 4 and the pusher plate 14 is always maintained at a constant value. Therefore, as in the above-described embodiment, the substantial resin reaction force can be accurately measured by the load cell 31.

Further, the bearings 42, 43 and the bearings 51, 52 for holding the ball screw 28 and the injection screw 5 rotatably and immovably in the axial direction are concentrically arranged to shorten the entire length of the injection mechanism. The fact that it is the same as that of the above-mentioned embodiment. The operations at the time of injection and at the time of kneading and kneading are also the same as those in the above-mentioned embodiment, so that the description thereof will be omitted.

FIG. 3 is a partial sectional side view showing still another embodiment of the injection mechanism to which the present invention is applied. The pusher plate 14 that presses the injection screw 5 includes a first pusher plate 14a and a second pusher plate 14b.
Means for integrally supporting the injection screw 5 rotatably and axially immovably and the ball screw 28 rotatably and axially immovably. 1 and 2 are arranged on the plates 14a and 14b while being shifted in the direction of the injection axis. The configuration is different from the above-described embodiments (in the configuration examples of FIGS. 1 and 2, each means is concentric). Have been deployed to).

The structure of the front plate 1, the injection cylinder 2, the rear plate 3, the guide rod 4, the ball nut 31, the load cell 33, etc. is the same as that of the embodiment shown in FIGS. And in this embodiment, as shown in FIG.
As shown in FIG. 7, the first pusher plate 14a and the second pusher plate 14b are arranged with a space therebetween, and the plate 14a and the plate 14b are integrally fixed by the tie rod 59. The second pusher plate 14b may be configured to be large and slidably attached to the guide rod 4 similarly to the first pusher plate 14a.

Then, the first pusher plate 14a
At the inner circumference of the through hole provided in the central part of the
The outer rings 0 and 61 are fixed, and the bearing 6
A screw sleeve 63 having an injection screw 5 and a screw rotation pulley 62 fixedly mounted on the inner races 0, 61.
The outer periphery of is fixed. The bearing 60 is an angular bearing having an outer ring for supporting a force acting on the inner ring from the left side in the figure, and the bearing 61 is a bearing for supporting a force acting on the inner ring from the right side in the figure. It is an angular bearing with an outer ring. The outer rings of the bearings 60 and 61 have a first annular mounting flange 64 for axially fastening the outer rings and a bolt 65 for fixing the mounting flange 64 to the first pusher plate 14a. Of the pusher plate 14a is integrally fixed to the inner circumference of a through hole provided in the central part of the pusher plate 14a, and the inner rings of the bearings 60 and 61 are screwed into a male screw threaded on the outer circumferential rear end of the screw sleeve 63. It is fastened together by an annular fixing member 66 that is fitted together in the axial direction, and is integrally fixed to the outer periphery of the screw sleeve 63. Bearings 60 and 61
Are means for rotatably supporting the injection screw 5 on the first pusher plate 14a so as not to move in the axial direction.

As shown in FIG. 3, the injection screw 5 is integrally fixed to the front end surface of the screw sleeve 63 via a screw mounting plate 69 and a bolt 67, and the front end surface of the screw sleeve 63 has an annular screw. The rotating pulley 62 is integrally fixed via a bolt 68. In addition, the first pusher plate 14a
A motor 35 for screw rotation is fixedly installed on one side of the
The pulley 62 is rotationally driven via the pulley 37 and the timing belt 39.

On the other hand, the bearing 7 is provided on the inner periphery of the through hole provided in the central portion of the second pusher plate 14b.
The outer ring 0,71 is fixed, and the bearings 70,7
A reduced diameter portion at the tip of the ball screw 28 is fixed to the inner ring of No. 1. The bearing 70 is an angular bearing having an outer ring for supporting a force acting on the inner ring from the left side in the figure, and the double-row bearing 71 supports a force acting on the inner ring from the right side in the figure. It is an angular bearing with an outer ring for. Bearing 70
The outer races 71 and 71 have a second pusher by an annular mounting flange 72 for fastening the outer races together in the axial direction, and a bolt 73 for fixing the mounting flange 72 to the second pusher plate 14b. The inner rings of the bearings 70 and 71 are integrally fixed to the inner circumference of a through hole provided at the center of the plate 14b, and the inner rings of the bearings 70 and 71 are male screws threaded on the outer circumference of the tip of the reduced diameter portion of the ball screw 28. A nut 74 that is screwed together is fastened together with a pulley 75 for injection drive, and is fixed to the outer periphery of the reduced diameter portion at the tip of the ball screw 28. Pulley 7 for injection drive
Reference numeral 5 is attached to the reduced diameter portion of the tip of the ball screw 28 via spline fitting, and cannot rotate with respect to the ball screw 28. The bearings 70 and 71 are means for supporting the ball screw 28 rotatably and axially immovably on the second pusher plate 14b. The center axis of the injection screw 5 and the center axis of the ball screw 28 are arranged to be the same.

A motor (servo motor) 36 for injection driving is fixedly installed on one side of the second pusher plate 14b, and the pulley 75 is rotationally driven via the pulley 38 and the timing belt 40. ing.

As in each of the above embodiments, the ball screw 28 is attached to the pusher plate 14 (second pusher plate 14
Since it is rotatably attached to b), the frictional resistance in the circumferential direction that acts on the screwing surface between the ball screw 28 and the ball nut 31 when the ball screw 28 is driven to rotate is the rotational moment about the injection axis as a rotation moment.
(The second pusher plate 14b and the first pusher plate 14a) do not act, and the sliding resistance between the guide rod 4 and the pusher plate 14 (the first pusher plate 14a) is always a constant value. Retained. Therefore, the load cell 31 is the same as in the above-described respective embodiments.
Thus, the substantial resin reaction force can be accurately measured.

Further, in this embodiment, since the injection driving pulley 75 is attached to the tip of the ball screw 28 protruding in front of the second pusher plate 14b, the nut 74 is simply removed. Pulley 7
5 can be performed, which is convenient when the pulley 75 is replaced and the reduction ratio of the drive system of the ball screw 28 is changed.

Since the operations during injection and metering and kneading are the same as those of the embodiment shown in FIGS. 1 and 2, their description will be omitted. FIG. 4 is a partial sectional side view showing still another embodiment of the injection mechanism to which the present invention is applied. Injection screw 5
The pusher plate 14 that presses is divided into a first pusher plate 14a and a second pusher plate 14b, and the rear plate 3 is sandwiched between the pusher plate 14a and the second pusher plate 14a.
Means for rotatably and axially immovably supporting the ball screw 28 and means for rotatably and axially immovably supporting the ball screw 28 are provided on the first pusher plate 14a side. The construction is different from the embodiment shown in FIG. 3 in that means for rotatably supporting the ball screw 28 is provided on the pusher plate 14b side.

In this embodiment, as shown in FIG. 4, the first pusher plate 14a and the second pusher plate 14b are arranged so as to be spaced apart from each other so as to sandwich the rear plate 3, and the plate 14a and the plate 14b are disposed.
And are fixed integrally by a tie rod 76. The rear plate 3 is provided with a through hole for passing the tie rod 76, and a bush 77 for slidably holding the tie rod 76 is fixedly provided on the inner periphery of the through hole.
The mounting direction of the ball nut 31 with respect to the rear plate 3 is different from that in each of the above-described embodiments. However, when the ball nut 31 is provided so as to project to the front side of the rear plate 3, the pusher plate 14 (first This is because the sliding stroke of the pusher plate 14a and the second pusher plate 14b) becomes short.

Then, the first pusher plate 14a
At the inner circumference of the through hole provided in the center of the
The outer rings of 8, 79 are fixed, and the bearings 78, 7
The outer periphery of a screw sleeve 80 having the injection screw 5 fixed thereto is fixed to the inner ring of 9. Bearing 78
Is an angular bearing having an outer ring for supporting a force acting on the inner ring from the left side in the figure, and the bearing 79 is provided with an outer ring for supporting a force acting on the inner ring from the right side in the figure. It is an angular bearing. The outer rings of the bearings 78 and 79 are annular mounting flanges 81 for fastening the outer rings together in the axial direction,
And the bolt 82 for fixing the mounting flange 81 to the first pusher plate 14a
Of the pusher plate 14a is integrally fixed to the inner circumference of a through hole provided in the center of the pusher plate 14a, and the inner rings of the bearings 78 and 79 are screwed into a male screw threaded on the outer rear end of the screw sleeve 80. It is fastened together by an annular fixing member 83 which is fitted together in the axial direction, and is integrally fixed to the outer periphery of the screw sleeve 80.

As shown in FIG. 4, the injection screw 5 is integrally fixed to the front end face of the screw sleeve 80 via a screw mounting plate 84 and a bolt 85, and the front end face of the screw sleeve 80 has an annular shape. A screw rotation pulley 86 is integrally fixed via a bolt 87.

The bearing 8 is provided on the inner periphery of the screw sleeve 80 by an annular fixing member 88 which is screwed into a female screw threaded at the rear end of the inner periphery of the screw sleeve 80.
The outer rings 9 and 90 are fixed, and the outer periphery of the tip of the ball screw 28 is fixed to the inner rings of the bearings 89 and 90. The bearing 89 includes an angular bearing having an outer ring for supporting a force acting on the inner ring from the left side in the drawing, and the bearing 90 has an outer ring for supporting a force acting on the inner ring from the right side in the figure. It is an angular bearing. The inner rings of the bearings 89 and 90 are axially fastened together by an annular fixing member 91 that engages with a male screw threaded on the outer periphery of the tip of the ball screw 28 having a reduced diameter, and the rear plate via the load cell 33. It is fixed to the tip of a ball screw 28 screwed into a ball nut 31 fixed to the No.

The screw rotating motor 35 is fixedly attached to one side of the first pusher plate 14a, and drives the pulley 86 to rotate via the drive pulley 37 and the timing belt 39.

On the other hand, on the inner periphery of the through hole provided in the central portion of the second pusher plate 14b, an annular fixing member 93 which is screwed into a female screw threaded at the rear end of the inner periphery of the through hole.
The outer ring of the bearing 92 is fixed by, and the reduced diameter portion of the rear end of the ball screw 28 is fixed to the inner ring of the bearing 92. The bearing 92 is a radial bearing having an outer ring for supporting a force acting in a radial direction on the inner ring. Second pusher plate 14b
A pulley 94 for injection driving is fixedly mounted on the rearmost end of the ball screw 28 protruding to the back surface of the ball screw 28, and a motor (servo motor) 36 for injection driving fixedly mounted on one side of the second pusher plate 14b causes The pulley 94 is rotationally driven via the drive pulley 38 and the timing belt 40.

Therefore, when only the motor 36 is rotationally driven, only the ball screw 28 rotates independently of the injection screw 5, and the ball nut 3 fixed to the rear plate 3 is rotated.
The axial screwing position of the ball screw 28 with respect to 1 changes, and the ball screw 28, the first pusher plate 14a attached to the ball screw 28 so as not to move in the axial direction, and the second pusher plate 14b integral therewith are moved forward or backward. This means that the injection screw 5 moves backward in the injection cylinder 2.

As in the above embodiments, the ball screw 28 is attached to the pusher plate 14 (first pusher plate 14).
a and the second pusher plate 14b), the frictional force in the circumferential direction acting on the screwing surface of the ball screw 28 and the ball nut 31 when the ball screw 28 is driven to rotate is about the injection axis. Of the pusher plate 14 (the first pusher plate 14a and the second pusher plate 14a
b), the sliding resistance between the guide rod 4 and the first pusher plate 14a and between the tie rod 76 and the bush 77 of the rear plate 3 is always maintained at a constant value. Therefore, similar to each of the above embodiments,
The load cell 31 can accurately measure a substantial resin reaction force.

Further, in this embodiment, the injection driving pulley 94 is attached to the rear end of the ball screw 28 projecting from the rear surface of the second pusher plate 14b located at the rearmost position of the injection mechanism. As with the embodiment shown in FIG. 3, the pulley 94 can be easily replaced, which is convenient when the pulley 94 is replaced and the reduction ratio of the drive system of the ball screw 28 is changed. Incidentally, also in this embodiment, the operations at the time of injection and at the time of kneading and kneading are the same as those of the previously described embodiment, and therefore the description thereof will be omitted.

[0054]

The injection mechanism of the injection molding machine according to the present invention comprises:
A ball screw is rotatably and immovably mounted on a pusher plate slidably attached to the guide rod, and the load cell is mounted on the rear plate integrated with the guide rod by rotating the ball screw. Since the screwing position of the ball screw with respect to the ball nut fixed through the shaft is changed in the axial direction to move the pusher plate that presses the injection screw,
Even if rotational friction occurs between the ball screw and the ball nut by rotationally driving the ball screw, the reaction force is not transmitted to the pusher plate via the ball screw. Therefore, the pusher plate attached to the guide rod does not generate a rotation moment around the injection axis, and the pusher plate does not hit the guide rod evenly. Therefore, the sliding resistance between the pusher plate and the guide rod is reduced. Is always held at a constant value.

The load cell interposed between the rear plate and the ball nut detects the resultant force of the substantial resin reaction force acting on the tip of the injection screw and the sliding resistance as an apparent resin reaction force. Since the magnitude of the sliding resistance between the pusher plate and the guide rod is always a constant value, by treating this constant value as a correction value etc. (even when performing mechanical zero point correction on the load cell, It is possible to accurately measure the substantial resin reaction force acting on the tip of the screw.

[Brief description of drawings]

FIG. 1 is a partial sectional side view schematically showing an injection mechanism of an embodiment to which the present invention is applied.

FIG. 2 is a partial sectional side view schematically showing an injection mechanism of another embodiment to which the present invention is applied.

FIG. 3 is a partial cross-sectional side view schematically showing an injection mechanism of still another embodiment to which the present invention is applied.

FIG. 4 is a partial cross-sectional side view schematically showing an injection mechanism of still another embodiment to which the present invention is applied.

FIG. 5 is a partial sectional side view schematically showing an injection mechanism of a conventional injection molding machine.

[Explanation of symbols]

 1 Front Plate 2 Injection Cylinder 3 Rear Plate 4 Guide Rod 5 Injection Screw 6 Pusher Plate 7 Bushing 8 Load Cell 9 Ball Nut 10 Ball Screw 11 Bearing 12 Bearing 13 Pulley 14 Pusher Plate 14a 1st Pusher Plate 14b 2nd Pusher Plate 15 Bearing 16 Bearing 17 Screw Sleeve 18 Screw Mounting Plate 19 Bolt 20 Screw Rotating Pulley 21 Bolt 22 Mounting Flange 23 Bolt 24 Annular Fixing Member 25 Annular Fixing Member 26 Bearing 27 Bearing 28 Ball Screw 29 Annular Fixing Member 30 Injection Drive Pulley 31 Ball Nut 32 bolts 33 load cell 34 bolts 35 screw rotation motor 36 injection drive Motors 37 Pulleys 38 Pulleys 39 Timing belts 40 Timing belts 41 Ball screw sleeves 42 Bearings 43 Bearings 44 Bolts 45 Injection drive pulleys 46 Bolts 47 Mounting flanges 48 Bolts 49 Annular fixing members 50 Annular fixing members 51 Bearings 52 Bearings 53 Screws Sleeve 54 Annular fixing member 55 Bolt 56 Screw rotating pulley 57 Bolt 58 Screw mounting plate 59 Tie rod 60 Bearing 61 Bearing 62 Screw rotating pulley 63 Screw sleeve 64 Mounting flange 65 Bolt 66 Annular fixing member 67 Bolt 68 Bolt 69 Screw mounting plate 70 Bearing 71 Bearing 72 Mounting flange 73 Bolt 74 Nut 75 Pulley for driving injection shaft 76 Tie rod 77 Bushing 78 Bearing 79 Bearing 80 Screw sleeve 81 Mounting flange 82 Bolt 83 Annular fixing member 84 Screw mounting plate 85 Bolt 86 Screw rotating pulley 87 Bolt 88 Annular fixing member 89 Bearing 90 Bearing 91 Annular fixing Member 92 Bearing 93 Annular fixing member 94 Pulley for driving injection shaft

Claims (6)

[Claims] 1. A pusher plate, to which an injection screw is attached, is slidably attached to a guide rod provided in parallel with the injection axis, and a rotational movement of the ball screw is converted into a linear movement by a combination of a ball screw and a ball nut. In an injection molding machine in which an injection screw is moved by pressing a plate, a ball screw is rotatably mounted on the pusher plate so as to be immovable in the axial direction, and a load cell is mounted on a rear plate integrated with the guide rod. An injection mechanism of an injection molding machine, wherein a ball nut is fixedly mounted through the screw, the ball screw is screwed into the ball nut, and the ball screw is rotationally driven to move the injection screw. 2. A screw sleeve having an injection screw fixed thereto is rotatably and axially immovably attached to the pusher plate, and is further fitted into the screw sleeve so as to be rotatable and axially immovable with respect to the screw sleeve. The injection mechanism of the injection molding machine according to claim 1, wherein a ball screw is axially supported on the shaft. 3. A ball screw sleeve having a ball screw fixed thereto is rotatably and axially immovably attached to the pusher plate, and further fitted inside the ball screw sleeve so as to be rotatable and axial with respect to the ball screw sleeve. The injection mechanism of an injection molding machine according to claim 1, wherein an injection screw is provided so as to be immovable and supported axially. 4. A means for rotatably supporting an injection screw rotatably and axially immovable on a pusher plate and a means for rotatably and axially immovably supporting a ball screw on a pusher plate. The injection mechanism of the injection molding machine according to claim 1, wherein the pusher plate is superposed on the pusher plate along the axial direction. 5. The first pusher plate is configured by integrally fixing a first pusher plate and a second pusher plate, which are arranged at a predetermined distance from each other in the injection axis direction, to constitute the pusher plate, and the first pusher. The plate is provided with means for rotatably and axially immovably supporting the injection screw, while the second pusher plate is provided with means for rotatably and immovably axially supporting the ball screw. The injection mechanism of the injection molding machine according to claim 4, wherein 6. The pusher plate is configured by integrally fixing a first pusher plate and a second pusher plate, which are arranged so as to sandwich a rear plate with a predetermined gap therebetween in the injection axis direction, The first pusher plate is provided with means for rotatably and axially immovably supporting the injection screw and means for rotatably and immovably axially supporting the ball screw. The injection mechanism of an injection molding machine according to claim 1, wherein the pusher plate is provided with means for rotatably supporting the end portion of the ball screw and means for rotationally driving the ball screw.